Incidence of major depression in a very elderly population

BACKGROUND: Depression is considered to be a major health problem in the elderly. Due to methodological problems, there are few studies on the incidence of depression in old age. The present study examines the prevalence of depression in a 3-year follow-up study of a non-depressed very elderly population, thus estimating the incidence. METHODS: 875 non-depressed persons with a mean age of 85 years were extensively examined by physicians twice with a 3-year interval. Depression diagnosis was made according to DSM-IV. All persons with a history of depression or a current depression were excluded in order to estimate the first incidence. RESULTS: 4.1% of the population was diagnosed as having a depression at the follow-up examination. The estimated first incidence was 1.4% per person year (0.8% in males and 1.5% in females). Characteristics at baseline correlated with the onset of depression were: having a dementia, insufficient social network and having more than two depressive symptoms. CONCLUSIONS: The incidence of depression was slightly lower in this very elderly population than for younger age groups, but followed the same female to male ratio.